ML19343C226

Addendum to AO 50-219/74/28 Dtd 740426:on 740419,motor- Operated Valve V-20-4 Failed to Open Electrically After Closing Electrically.Caused by Premature Opening of Position Switch 20-C.Position Switch Readjusted

ML19343C226
Person / Time
Site:	Oyster Creek
Issue date:	07/11/1974
From:	JERSEY CENTRAL POWER & LIGHT CO.
To:
References
AO-50-219-74-28, NUDOCS 8103040512
Download: ML19343C226 (2)

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ADDENDUM Abnormal Occurrence Report No. 50-219/74/28 Abnormal Occurrence Report No. 50-219/74/28, occurrence date April 19, 1974, reported that motor-operated valve V-20-4 failed to open electrically after closing electrically in a normal manner during the perfomance of surveil-lance testing on core spray system II. Since valve V-20-4 provides suction to the "B" core spray pump, core spray pump redundancy was lost in system II during the period of time that the valve was stuck in the closed position. Immediate corrective action involved manually opening the motor-operated valve (V-20-4) and tagging open the associated circuit breaker to prevent subsequent closing.

Since core spray system I was tagged out for maintenance at the time of this abnomal occurrence, it was not immediately possible to troubleshoot and detemine the cause of the V-20-4 failure. Consequently, the initial abnomal occurrence report did not identify the cause of the valve failure.

The purpore of this addendum is to report the apparent cause of the failure, additional items of corrective action and pertinent failure data.

Apparent Cause of Occurrence Refer to the attached schematic diagram of the opening and closing control circuitry for V-20-4 (Figure 1). Torque switch TS-0 is provided to interrupt the control circuitry if a mechanical overload occurs during the opening cycle. Fosition switch 20-C is provided to override the function of TS-0 during the initial stages of the opening cycle. This position switch (20-C) is normally adjusted to open at approximately 10% of valve travel.

Investigation of the control circuitry after the abnormal occurrence revealed that 20-C was opening prematurely at 6t, to 7% of valve travel. It has, therefore, been concluded that 20-C opened before torque switch TS-0 closed, thereby preventing V-20-4 from opening.

Additional Corrective Action Position switch 20-C was readjusted to open at approximately 105 of valve travel.

Failure Data Manufacturer data pertinent to the V-20-4 valve control are as follows:

Manufacturer: Limitorque Model No. : 391667-ES Motor HP: .67 P00R ORIGINAL vmwwa

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9 Figtire 1 Opening And Closing Control Cirettitry For V-20-4 e . .. ._. . . - - . 120VAC . . . . . _ . . . . . _ _ _ . _ _ _ _ _ . . .,

20-IC T:i-0 110 hC 30L 204 10L

- _. I s  ! - . / N. _

j l. l__._ ., _g._g. f -

i 6A 6 4 3

- - F-- . kbf (12) 20-C i

.(D.]l_(8)_ '

305 B i

' - 4

. _._ { } ,

i i

TS-C 16K107B 305B .510 p._ ,.. /N . . , . _ , _ . g_ __. , _

. ... l [1T 16K107D 11C 6D 6C 2C-0 (1) (2) 20-10

/ t i

._{ p_-_.... . .. .

R - -- ----- l 20-IC /

I

.. _ _ . . l _ { . _ . .._ . . . . _ .

g n

IC - Closed during 1st 90% of Travel 10 - Open after 1st 10's of Travel TS Torque Switch Open TS-C - Torque Switch closed b!0 - h!otor Open b!C - Flotor Closed J

P00R ORIGINAL